1. Field of the Invention
The present invention relates generally to marine air conditioning systems and relates specifically to a system having a water-cooled condenser.
2. Description of the Related Art
For many years, air conditioning units have been installed on boats to provide comfortable areas on the boat during warm weather. Various methods of cooling the air on the boat have been used, including non-refrigerant cooling systems. However, a system using a compressed refrigerant is the most effective system in widespread use today.
In typical marine air conditioning systems, an electric motor drives a compressor for compressing refrigerant within a closed-system. The refrigerant becomes heated as it is compressed, and it then passes through a condenser for cooling the refrigerant. The condenser may be an air-cooled unit, in which air passes over tubing in the condenser for drawing heat from the refrigerant as it passed through the condenser. Another type uses water to cool the refrigerant, in which a pump draws water through a hole in the hull of the boat and over the condenser tubes. Either method sufficiently cools the refrigerant.
One disadvantage of using the current systems is that the electric motor typically requires the boat to be docked and connected to an outboard electrical source or to have an onboard generator. Without a generator, the system cannot be used when the boat is away from a dock. A disadvantage of a water-cooled system is that the system requires a separate water pump to pass water through the condenser. A related disadvantage is the additional holes in the hull that are required for the inlet and outlet of the pump for the condenser.
Many systems are available that use engine-driven compressors for compressing the refrigerant. However, these systems also use air-cooled condensers or water-cooled condensers that utilize a water pump in addition to that providing water to cool the engine.
Therefore, there is a need for a marine air conditioning system having a water-cooled condenser and that eliminates the need for a separate water pump for the condenser and the associated additional holes in the hull. There is also a need for such a system that is operable while away from a dock.
A marine air conditioning system for installation on a boat comprises a compressor, a water-cooled condenser, and an evaporator. The compressor is preferably directly driven by an engine used for propelling the boat. The condenser is installed inline in a cooling-water intake tube, through which a pump draws raw water from outside of the hull for cooling the engine. The raw water from the intake tube is drawn through a portion of the condenser in thermal communication with the refrigerant for transferring heat from the refrigerant to the water. The raw water then continues into the engine cooling system and is exhausted through a discharge tube. The refrigerant passes through an expansion valve, and then into the evaporator. Air is passed through the evaporator for cooling the air, and the refrigerant returns to the compressor for recirculation in the system.